1. Field of the Invention
The present invention relates to the field of liquid crystal displaying, and in particular to a method for forming a reflector and a reflective liquid crystal display (LCD) manufactured with the method.
2. The Related Arts
The displays that are currently available in the market are generally classified in three categories, namely transmissive LCD, reflective LCD, and transflective LCD, according to the liquid source used thereby. The transmissive LCD is fit for environments with weak lighting, such as being used indoors. For use outdoors, when an external light source is intense, the intensity of the backlight source is generally affected by the external lighting, making the eyes of a viewer, when watching the display panel, perceiving the display panel being excessively bright and thus not clear. This affects the image quality. Further, long term use of the backlight source generally consumes a great amount of electrical power. For small-sized displays, which are generally powered by batteries or cells, they often run out of power very quickly. The reflective LCD is fit for sites where strong external lighting exists, because a reflector is provided in the structure thereof to reflect the strong external light and thus alleviate the influence caused by the external lighting. Such a structure is thin and compact and consumes less power. However, insufficiency of light intensity may occur in sites where lighting is weak, thus affecting the image quality. Since the reflective LCD is advantageous for thin and compact structure and saving power, it is widely applied to portable liquid crystal displays. The transflective LCD has two different displaying modes. In a dark environment, the transmissive mode works, namely a backlight source of the LCD emitting light to transmit through a liquid crystal panel to display image, and in an environment of sufficient lighting, such as sunlight, the reflective mode works, namely a reflector inside the liquid crystal panel reflecting the external light to serve as a light source for displaying of image. Thus, the transflective LCD is fit for various external environments with different lighting intensities and is especially advantageous of having excellent outdoor viewability and requiring no great brightness of the backlight source and consuming less power.
A reflective LCD comprises an upper substrate, a lower substrate attached to the upper substrate, and liquid crystal interposed between the upper substrate and the lower substrate. A reflector is arranged on the lower substrate.
However, the reflection surface of a regular reflector is quite flat so that a portion of light that does not pass through and is thus not refracted by the upper substrate reaches and is thus directly reflected by the reflector of the lower substrate, while the remaining light passes through and is refracted by the upper substrate to enter the lower substrate and is subjected to reflection at the reflector of the lower substrate and then passes through and is refracted again by the upper substrate to leave the upper substrate. The two portions of light are of the same angle and thus interference results. This directly affects parameters of reflective LCD, such as the contrast and sharpness.
Based on the above described problems, the conventional reflective LCD often provides a tilt angle on the reflector of the lower substrate in order to induce scattered reflection to alleviate such an influence. However, this solution suffers the following issues:
(1) Masking operation and yellow light process must be used and the installation and labor costs are high;
(2) Layout must be effected on mask in forming the tilt angle and the quantity and direction of the tilt angle are fixed so that the scattered reflection induced thereby is only effective in a limited area and in an actual operation, mirror reflection may be linearly generated in localized areas; and
(3) Techniques related to gray tone mask and half tone mask that shows variable local exposures must be adopted and the manufacture cost and yield control cost of these techniques are relatively high.